(Yes, the trains would be long enough that the platform would have one end at Euston and the other at Kings Cross. Crossrail 1 has similar stations, one at Farringdon/Barbican and another at Liverpool Street/Moorgate, and even Thameslink, after its recent upgrades, has a station with entrances on both sides of the Thames.)

It would also link happily to the High-Speed 2 terminus in Euston, put a new station in the railway black-hole of inner Chelsea, and join up the two southern spurs of the Northern and District line. The consortium has clearly put a lot of thought into the plans, and if someone can be found to stump up the estimated £12bn cost, it will fix London's public transport congestion for at least, ooh, a year or so. After that, London could have its south London monorail or its cross-river tram.